The eastern coast would continue to be volatile and susceptible to thunderstorm activity for the most part until Tuesday next (April 6), according to the US National Centres for Environmental Prediction (NCEP).

As if on cue, India Meteorological Department (IMD) said in its update on Wednesday that a weather-making trough ran down the eastern flank from Bihar to Tamil Nadu across Jharkhand, Orissa and Andhra Pradesh.

The US forecaster was also of the view that the ongoing thunderstorm activity in the northeast would witness flare-ups on Thursday before the active thunderheads migrate to the north of the region.

The IMD forecast said that fairly widespread rain/thundershowers accompanied with isolated thunder squall would occur over the north eastern States during the next two days and decrease, thereafter.

Low to medium clouds (partly clouded conditions) were traced to over parts of Jammu and Kashmir, Himachal Pradesh, Uttarkhand, sub-Himalayan West Bengal, Sikkim, Orissa, Andhra Pradesh, south Karnataka, Kerala, Tamil Nadu, the north eastern States and south Andaman Sea.

Isolated heavy rainfall accompanied with thunder squall is likely to occur over Arunachal Pradesh, Assam and Meghalaya during the two days.

Moisture incursion too would continue over the north eastern States during this period.

EASTERLY WAVE

This, according to the NCEP, would be followed by an apparent loss in intensity towards the immediate south, but matched only by the drumming up of activity in the extreme southeast Bay of Bengal in the form of an easterly wave.

Thundershowers spearheading the wave are forecast to hit the eastern coast of Sri Lanka by April 5.

The rains would enter mainland India along the southeast Tamil Nadu coast by the next day and onward to interior Tamil Nadu and adjoining southern Kerala.

According to the European Centre for Medium-Range Weather Forecasts (ECMWF), a dry weather-making ridge (high-pressure region) extending from northwest and adjoining central Pacific would have pushed its way into the peninsular east coast as early as this Saturday.

The ridge would gradually extend its influence further west into the peninsula and into the Arabian Sea beyond, leaving a trail of intense tropical heat.

The heat wave would cover the west-central peninsula and head north-northwest into west Madhya Pradesh, Gujarat and west Rajasthan.

The causative ridge is shown to hold strong until April 10 up to which forecasts were available, and may start receding from the Arabian Sea and into mainland India immediately after.

Indications are that the extreme south peninsula would be spared of the ‘top heat' and would witness welcome visitations by thunder storms marching in west over the Bay of Bengal.

A fresh western disturbance is likely to affect western Himalayan region from Friday but may not have a significant impact on weather in the North-East.

The IMD expected heat wave conditions to continue over parts of north Madhya Pradesh, Chhattisgarh and interior Orissa during the next 24 hours.